[ Pharmaceutical Sciences Asia - ONLINE ]
E-ISSN 2586-8470
[ Journal Abbreviation: Pharm.Sci.Asia ]
Mahidol University Journal of Pharmaceutical Sciences
  FORMER NAME   "Mahidol University Journal of Pharmaceutical Sciences" Published Since 1974


DOI: 10.29090/psa.2018.04.017.0061Pharm Sci Asia 2018; 45(4), 231-235

Microbiological quality of commercial Thua Nao, a Thai fermented soybean product

Kamonsri Suriyanoi1, Pawida Chumpurat1, Ross A. Beamon1, Worawut Suvegoon1, Ugrit Suksai2, Ekachai Chukeatirote1*

1 School of Science, Mae Fah Luang University, Thailand
2 Department of Medical Sciences, Chiang Rai Regional Medical Sciences Center, Ministry of Public Health, Thailand

Thua Nao, a Thai fermented soybean product, is widely used as a condiment in many northern food. Although it is generally known that Bacillus species are predominant and thus play a key role during the soybean fermentation, information regarding other microbial population is limited. Besides, Thua Nao has currently been produced traditionally (i.e. by naturally occurring microbes) and this may raise a concern regarding food safety. This present study hence aimed to evaluate the microbiological quality of Thua Nao products sold in local markets of Chiang Rai and Phayao Provinces, Thailand. In total, twenty-four Thua Nao products (9 fresh and 15 dried samples) were collected from different local markets in Chiang Rai (20 samples) and Phayao (4 samples). Microbiological analyses were carried out for a total count of mesophilic aerobic bacteria (TMAB) and fungi; the presence of some pathogenic bacteria was also evaluated including Bacillus cereus, Escherichia coli, Clostridium perfringens, Staphylococcus aureus, and Salmonella species. Our data revealed that high levels of TMAB (>105 CFU/g) and moulds (>104 CFU/g) were found in most samples. Escherichia coli, Salmonella spp. and Bacillus cereus were detected in which E. coli was the most frequently isolated pathogenic bacteria accounting for 54.17% of the samples studied. However, our results showed that C. perfringens and S. aureus were not found in all samples. Based on this finding, commercial Thua Nao products prepared traditionally may not be hygienic. Practical guideline and monitoring of this microbial contamination should be implemented to ensure safer food for the consumers.


Thua Nao; Fermented soybean; Foodborne pathogen; Microbiological quality

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